Laser diode array

ABSTRACT

A process of making a laser diode device includes these steps: applying a bonding layer such as molybdenum manganese to surfaces of first and second bodies of dielectric material such as beryllium oxide; joining the first and second bodies together to form a cavity; and bonding a sectored conductor ring to the bonding layer within the cavity.  
     The laser diode device made by the process includes a body of dielectric material such as beryllium oxide forming a cavity; a bonding layer lining the cavity; a conductor bonded to the layer within the cavity; the conductor being divided into ring sectors separated by radial diode bar spaces; and a laser diode bar in each of the bar spaces forming an array of such laser diode bars. The ring sectors and laser diode bars together form a series path for electric current around the conductor to energize the laser diode bars.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] This invention relates to a laser diodes mounted in an array,surrounding a laser medium for excitation thereof, and particularly tothe fabrication and structure of the surrounding array.

[0003] 2. Background Information and Disclosure

[0004] Excitation of a laser medium from an adjacent or surroundingarray of laser diodes is known in the prior art.

[0005] U.S. Pat. No. 5,033,058 to Cabaret et al discloses a laser rod ina glass tube with a segmented reflective coating. Laser diodes placedaround the glass tube emit through windows in the reflective coating toexcite the laser rod.

[0006] U.S. Pat. No. 5,040,187 to Karpinski, and U.S. Pat. No. 5,128,951to Karpinski both disclose flat laser diode arrays mounted in a ceramicsubstrate with a metallized surface. Current through the metallizedsurface energizes the laser diodes, which then excite an adjacent lasermedium, not shown in the patents.

[0007] U.S. Pat. No. 5,521,936 to Irwin discloses a radial array oflaser diodes mounted in a sectored conductive ring surrounding a laserrod. An inner tube forms a coolant channel around the laser rod, and anouter sleeve forms a coolant channel around the ring and the laserdiodes.

[0008] The most relevant prior art that I know of is U.S. Pat. No.5,627,850 to Irwin et al. It discloses a laser diode array whichincludes a dielectric block with a conductor layer “direct bonded” toit. The conductor layer is divided into sectors by spaced diode barspaces. A laser diode bar is positioned in each space. The conductorlayer and laser diode bars together surround a laser medium which isexcited by the laser diode bars.

SUMMARY OF THE INVENTION

[0009] This invention is a laser diode device, and a process of makingit. The process includes these steps: applying a bonding layer such asmolybdenum manganese to surfaces of first and second bodies ofdielectric material such as beryllium oxide; joining the first andsecond bodies together to form a cavity; and bonding a sectoredconductor ring to the bonding layer within the cavity.

[0010] The device includes a body of dielectric material such asberyllium oxide forming a cavity; a bonding layer lining the cavity; aconductor bonded to the layer within the cavity; the conductor beingdivided into ring sectors separated by radial diode bar spaces; and alaser diode bar in each of the bar spaces forming an array of such laserdiode bars. The ring sectors and laser diode bars together form a seriespath for electric current around the conductor to energize the laserdiode bars.

DRAWING

[0011] FIGS. 1-6 are cross-sectional views of various stages offabrication of a laser and diode array according to this invention.

DESCRIPTION

[0012] The following is a description of the fabrication of a laserdiode array according to this invention.

[0013]FIG. 1 shows a lower block 10 of dielectric material, preferablyberyllium oxide (BeO). The block 10 includes a cavity 11 which issemi-cylindrical in the example shown.

[0014]FIG. 2 shows the semi-cylindrical cavity lined with a layer ofbonding material 12, preferably molybdenum manganese (MoMn). The bondinglayer 12 is a metalized coating applied by painting, spraying,sintering, or screen printing on the BeO surface.

[0015]FIG. 3 shows a conductor ring 13 mounted in the semi-cylindricalcavity of the lower block 10, and bonded to its bonding layer 12,preferably by copper-silver solder. An upper block 10, similar to thelower block and inverted relative to it, is mounted over the conductorring 13 which is then is similarly bonded to the upper block 10.

[0016]FIG. 4 shows the conductor ring 13 including a number of radialdiode bar spaces 21, dividing the ring 13 into a plurality of ringsectors 20 a, 20 b, 20 c, etc. (see also FIG. 5). The diode bar spaces21 may be expanded at their radial inner and outer ends 22, 23. The ringsectors may each include a stress relief groove 24.

[0017]FIG. 5 shows a laser diode bar 25 mounted in each bar space 21, acoolant tube 16 of a dielectric material mounted within the conductorring 13, and a laser medium 26 mounted and centered within the coolanttube 16, whereby laser and tube together form an annular coolant flowchannel 18 around the laser medium 26. The channel 18 is a conduit forwater to remove heat from the laser medium 26. The laser diode bars 25are held in the bar spaces 21, preferably by solder. The ring sectors 20and laser diode bars 25 mounted between them together form a series pathfor electric current around the conductor ring 13.

[0018]FIG. 6 shows the device of FIG. 5 in operation. With electriccurrent through successive ring sectors 20 and laser diodes 25 mountedbetween them, the laser diodes 25 emit light which in turn energizes thelaser medium 26. FIG. 6 also shows the symmetry of pumping actionproduced by the array of laser diodes.

[0019] The bonding layer 12 between the dielectric blocks 10 and theconductor ring 13 is an improvement over the “direct bond copper”technique disclosed in U.S. Pat. No. 5,627,850, discussed above. Thebonding layer 12 forms a stronger, more reliable bond with the BeOblocks.

[0020] In the devices described, the conductor ring 13 is preferablycopper because of its thermal and electrical conductivity, and theblocks 10 are preferably beryllium oxide because it is a thermallyconductive dielectric. Some other ceramic or oxide such as alumina couldbe used, for example in a configuration where thermal conductivity ofthe block is not so important.

[0021] The foregoing description of a preferred embodiment of thisinvention sets forth the best mode contemplated by the inventor ofcarrying out this invention. Specific details as to materials,quantities, dimensions, and the like are intended as illustrative andnot limiting, except as limited by the following claims. The concept andscope of the invention are limited only by the following claims andequivalents thereof.

What is claimed is:
 1. A process of making a laser diode device,including the following steps: (a) applying a bonding layer to a cavitysurface of a first body of dielectric material; (b) applying a bondinglayer to a cavity surface of a second body of dielectric material; (c)bonding a conductor ring to said bonding layer of said first body; (d)mounting said second body over said first body and said conductor ring,whereby said said first and second bodies together substantiallysurround said conductor ring; and (e) bonding said conductor ring tosaid bonding layer of said second body
 2. A process as defined in claim1, in which said bonding layer is molybdenum manganese.
 3. A process asdefined in claim 1, in which said cavity surface is semi-cylindrical andsaid conductor ring is a sectored conductor ring.
 4. A process asdefined in claim 1, in which said bonding is by copper-silver solder. 5.A process as defined in claim 1, in which said dielectric material isberyllium oxide.
 6. A process of making a laser diode device, includingthe following steps: (a) applying a bonding layer to a cavity surface ofa first body of dielectric material; (b) applying a bonding layer to acavity surface of a second body of dielectric material; (c) joining saidfirst and second bodies together to form a closed cavity therebetween;and (d) bonding a conductor ring to said bonding layers of said firstand second bodies.
 7. A process as defined in claim 6, in which saidbonding layer is molybdenum manganese.
 8. A process as defined in claim6, in which said cavity surface is semi-cylindrical and said conductoris a sectored conductor ring.
 9. A process as defined in claim 6, inwhich said bonding is by copper-silver solder.
 10. A process as definedin claim 6, in which said dielectric material is beryllium oxide.
 11. Alaser diode device, including: (a) a body of dielectric materialdefining a cylindrical cavity; (b) a bonding layer lining said cavity;(c) a sectored conductor ring bonded to said layer within said cavity,said conductor ring including separate ring sectors with radial diodebar spaces between adjacent sectors; and (d) a laser diode bar disposedin each of said bar spaces in an aray of said laser diode bars; saidring sectors and said laser diode bars together forming a series pathfor electric current around said conductor ring to energize said laserdiode bars.
 12. A laser diode device as defined in claim 11, in whichsaid bonding layer is molybdenum manganese.
 13. A laser diode device asdefined in claim 11, in which said cavity and said conductor ring arecylindrical.
 14. A laser diode device as defined in claim 11, in whichsaid conductor ring is bonded to said film by copper-silver solder. 15.A laser device as defined in claim 11, in which said dielectric materialis beryllium oxide.
 16. A laser diode device, including: (a) a pluralityof blocks of dielectric material joined together to form a cylindricalcavity; (b) a bonding layer lining the inner wall of said cavity; (c) asegmented conductor ring bonded to said layer within said cavity, saidconductor ring including separate ring sectors with radial diode barspaces between adjacent sectors; and (d) a laser diode bar disposed ineach of said bar spaces; said ring sectors and said laser diode barstogether forming a series path for electric current around saidconductor ring to energize said laser diode bars.
 17. A laser diodedevice as defined in claim 16, in which said bonding layer is molybdenummanganese.
 18. A laser diode device as defined in claim 16, in whichsaid cavity and said conductor ring are cylindrical.
 19. A laser diodedevice as defined in claim 16, in which said conductor ring is bonded tosaid layer by copper-silver solder.
 20. A laser device as defined inclaim 16, wherein said dielectric material is beryllium oxide.